While shopping for motion sensors to secure your home, you might be a little leery about the seemingly fancy technology used. If you know more about how they work, you’ll be able to make better, informed shopping decisions, and as a result end up with a safer home. While no one has the time to really learn every single detail about every tool that they use, a basic grasp of the concepts that are utilized in motion sensor alarms will save you plenty of headaches later on!
There are actually many different ways a motion sensor can work. For instance, ultrasonic methods that worked by bouncing waves off a target and listening to the resulting echoes was a very popular method for alarms at one point, although it has since been rendered somewhat outdated. For stores, if you’re wondering how doors open automatically and how bells ring as soon as you walk in, these are sensors that work primarily by radar or photosensors. However, the common motion sensor alarm used for home nowadays is based more or less entirely on infrared.
Instead of relying on listening for echoes or monitoring beams of light, motion detector alarms intended for home use make use of infrared to monitor the heat signatures in a given area. These motion sensors are attuned to trip when detecting bodies of heat within a human temperature range.
The catch to this is that a motion sensor burglar alarm that is overly sensitive to heat signatures will go off all the time, for reasons as minor as a dog walking nearby or sidewalks shedding heat overnight. To prevent this, alarms are rigged to only respond to rapid signature changes such as those involved in human motion. This means that someone can technically avoid tripping an alarm if he stands completely still… forever, making it an impractical defense for burglars to use! Alarms are also set to ignore heat signatures below a human weight level. This keeps them from going off due to random animal presences, for instance, and is a real boon to pet owners.
Infrared is a versatile, useful, and very safe methodology for alarms to work by, but it does have its limitations, despite the many advances in the field. For instance, for better or worse, infrared has great difficulty passing through glass. This means that windows are an effective barrier to motion detection as it’s used in most home security devices. If you have a greenhouse out in your yard, to keep it fully secure you’ll need to rely on more than just your yard security system. The glass will necessitate acquiring an extra security system for the inside of your greenhouse as well. However, for the common home owner, this limitation isn’t a major issue, and generally shouldn’t come up when buying a system for an ordinary house or apartment.
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